Swinging and processing whole tree, tree length, and log length pieces in a Douglas-fir thinning

This paper describes a study done on swinging and\ud processing whole tree, tree length and log length\ud pieces in a smallwood Douglas-fir thinning. Two machines\ud were evaluated, a 70 horsepower rubber tired\ud skidder and a hydraulic loader mounted on a 6 x 4 live\ud tandem truck.\ud The study took place in the foothills of the Coast\ud Range in western Oregon. The stand averaged 217\ud trees/acre and 15 ft3/tree. Skidder and loader swinging\ud occurred on rock surfaced truck roads.\ud Both the loader and skidder were analyzed using\ud work sampling and detailed time study techniques. Regression\ud analysis was used to develop an equation to\ud predict delay free turn time for the skidder.\ud The whole tree/tree length skidder operation produced\ud 2.74 cunits/scheduled hour at $16.45/cunit for\ud a two man crew and $22. 61/cunit for a three man crew.\ud There was no difference in production rates. A comparable\ud two man log length operation produced 3.41\ud cunits/scheduled hour at $23.51/cunit. This higher\ud cost included limbing and bucking done at the stump.\ud The whole tree/tree length loader operation produced\ud 3.21 cunits/scheduled hour at $16.15/cunit.\ud Crew interaction was evaluated using work sanipling.\ud For the skidder operation, interference was nonexistent,\ud the equivalent of almost one man was idle\ud (93.8%) on the three man crew, and idle time ranged\ud from 35-52% for the chaser and 12-18% for the skidder\ud operator. For the loader operation, interference time\ud was 7.1% for the loader and 9.7% for the chaser, and\ud idle time was 30.1% for the loader and 37.5% for the\ud chaser. All percents were based on total scheduled\ud time.\ud For the skidder assisted operation, limbing and\ud bucking production and cost rates were 1.82 cunits/scheduled\ud hour for $13.19/cunit at the stump and 6.54\ud cunits/scheduled hour for $6002/cunit on the landing.\ud Fallers removed an average of 30.27 limbs/tree at\ud the stump while landing crews removed 5.23 limbs/tree.\ud Yarding and swinging knocked of f the difference.\ud Slash, consisting of limbs and tops, averaged\ud 4.95 ft3/tree. Slash handling accounted for 2% of\ud total time for the skidder and 18% for the loader.\ud All breakage occurred on the skidder operation.\ud Eleven pieces were broken resulting in 0.2% of the\ud total gross volume being lost. All of these were on\ud corridors where the angle with the truck road required\ud the logs to be turned more than 90 degrees